Highbush blueberry (Vaccinium corymbosum L.), originally a forest plant, is currently in need of improvement of clonal micropropagation technologies. It is known that the large percentage of propagated plants can be lost or damaged, not only at the stage of acclimatization to non-sterile conditions, but also during the growing completion stage. In fact, successful ex vitro regeneration of such plants is determined by their ability to produce new shoots that can adapt to new cultivation conditions. The lighting and ratio of nutrients under ex vitro conditions play an important role in the development of the plants’ photosynthetic capacity. The research revealed that LED grow lighting has a positive effect on the development of ex vitro plants of highbush blueberry (Vaccinium corymbosum L.) cv. Brigitta Blue, only at the initial stages of growing in 0.5-L containers. The results obtained have improved our understanding of lighting and mineral fertilizer’s impact on the development of ex vitro plants of the highbush blueberry (Vaccinium corymbosum L.) cv. Brigitta Blue in greenhouse conditions. This can be useful for providing blueberry planting stock and commercial use for large scale production.

The element iron plays a key role in plant physiology. For plant nutrition, chelated forms of iron are preferred. Therefore, in clonal micropropagation media, FeSO4 x 7H2O is usually introduced together with Na2EDTA. At the same time, other effective iron chelates with both carboxyl and phosphorus chelates are known. So far, there are few scientific studies on the effect of iron chelates complexes on blueberry plants under in vitro conditions. Therefore, studies were conducted with different iron chelate complexes in 4 concentrations on highbush blueberry (Vaccinium corymbosum L.) cv. Brigitta Blue in clonal micropropagation technology. The best results were obtained using Fe(III)-DTPA in increased (×1.5) and doubled (×2.0) concentrations, where the multiplication factor was 4.59-4.65.

This study was conducted to evaluate the morphological and morphometric characteristics of a sparsely distributed berry crop – Empetrum nigrum L. cultivar Irland in 2023-2024 during in vitro culture initiation and multiplication stages. The results showed that the best growth-stimulating hormone for sterile culture initiation is – 6-BAP at a concentration of 0.2 μM, at which the grafting rate of explants was 73.3%. As a result of the studies, at the multiplication stage, the advantage of using Zeatin (2.2 μM) as a growth-stimulating hormone when using agar-agar AT (American type) as a gel-forming agent was revealed, and the productivity of microshoots was 3.68 times higher than that of the control.

Timeliness.The prerequisites for the cultivation of bog cranberry (Vaccinium oxycoccosL.) in industrial plantations have led to an increased demand for high quality planting material obtained by clonal micropropagation (in vitro). Studies have been carried out on the ofex vitrogrowing completion of cranberry plants using different mineral fertilizers and types of light under greenhouse conditions.Methods.Ex vitroplants of a selected form of cranberry (Vaccinium oxycoccosL.) obtained using the clonal micropropagation technique were the objects of research. Experimental adapted cranberry plants were planted in 0.5 L containers in 'Veltorf' peat substrate with an acidity of at least pH 3.5-4.0, to which mineral fertilizers were added according to the variants: APAVIVA N15P15K15(S10) 0.08 and 0.16 g/L, Sulfoammophos N16P20(S12) 0.072 and 0.144 g/L, N12P52 0.1 and 0.2 g/L, control without fertilizer. The plants were placed under different types of light: under LED phytolamps (UnionPowerStar – 40W-T) with a photoperiod of 16 hours and under natural light (without the use of additional lighting) under greenhouse conditions.Results. It was found that during of theex vitrogrowing completion of bog cranberry (Vaccinium oxycoccosL.) plants in containers, the advantage of LED phytolamps was revealed, when using them in all experimental variants on the 42nd day of growing the morphometric indicators of plant development were almost 2 times higher than in plants grown under natural light. The type of mineral fertilizers and type light significantly influenced the total length of shoots (82.9±13.74- 107.4±35.95 cm vs. 58.6±20.92 cm in control) and leaf surface area (41.1±6.46-54.1±4.67 cm2 vs. 22.9±9.63 cm2 ).Conclusion.The results we obtained contributed to a better representation of theex vitrogrowing conditions of bog cranberry (Vaccinium oxycoccosL.) plants using different types of lighting (phyto-lighting with a 16-hour photoperiod and natural light – without adding additional light) and the selection of optimal doses of mineral nutrition. The best, under LED lighting, were N16P20(S12) at a concentration of 0.072 g/L and N15P15K15(S10) at a concentration of 0.16 g/L.

Empetrun nigrum L. is a rare berry crop with a high content of biologically active substances, which are of great interest in medicine. In order to obtain sufficient transplants of this crop, in vitro propagation is preferred over other methods. It is known that a large percentage of propagated plants can be lost or damaged, not only at the stage of adaptation to non-sterile conditions, but also in the post-adaptation period. Plants may have weak growth due to poor root development and a lack of nutrients. Therefore, to improve the understanding of the plant requirements in the post-adaptation period of E. nigrum, clonal micropropagation was performed by combining mycorrhizal preparations containing (1) mycelium of Glomus sp., and humic substances, and (2) mycelium of Glomus sp., Trichoderma harzianum, and other mycorrhiza formation microorganisms with different types of mineral fertilizer (N₂₀P₂₀K₂₀, N₂₀P₁₆K₁₀(S₅), and N₁₉P₉K₁₀ + 2MgO). Analysis of the growth dynamics of ex vitro plants over 98 days of cultivation in containers under greenhouse conditions showed the effectiveness of mineral fertilizer and mycorrhizal preparations treatment. The total root length increased by 30–50% and the total shoot length by 40–80%. The survival was 95.8–100%.

Relevance. Black crowberry ( E. nigrum L.) is a wild plant that contains high levels of biologically active substances. It is currently attracting increasing interest as both a berry and a medicinal plant. Therefore, it has potential for cultivation as a source of medicinal plant material containing high amounts of flavonoids. There is therefore a need to develop accelerated methods of vegetative propagation, including clonal micropropagation. A critical step in this process is adapting the plant to non-sterile conditions. The aim of our research was therefore to develop methods for adapting and inducing rhizogenesis ex vitro of microcuttings of black crowberry ( E. nigrum L.) cultivar 'Irland' grown on various substrates using different rooting stimulants. Methods. The study focused on unrooted microcuttings of black crowberry ( E. nigrum L.) plants of the 'Irland' variety, which were obtained through clonal micropropagation in vitro. The crowberry microcuttings were planted in the third ten-day period of November in mini-greenhouses in various substrates (high-moor peat with pH _KCl ≤ 3.5-4.0, sphagnum moss, and agroperlite). Experimental microplants treated with root formation stimulants ('Radygreen zelonyy', 'Mycofriend', 'BioKoren', 'KorneWin Ultra') were planted in these substrates. The control variant was a variant without treatment. The mini-greenhouses were located under Zěma ZML-0160 LED phytolamps, with a photosynthetic photon flux density (PPFD) of 120 µmol·s ⁻¹ ·m ⁻² at a distance of 50 cm from the plants, with a 16/8-hour (light/dark) photoperiod for 45 days. After adaptation to non-sterile conditions, the plants were maintained in a greenhouse (temperature 22-30 ºC, air humidity 70-75%). Results. On the 45th day of adaptation and rooting process of the black crowberry microcuttings', the advantages of cultivating them on an inorganic substrate agroperlite and treating the basal parts of the microcuttings with the mycorrhiza-forming preparation ‘Mycofriend’ was revealed. With a rooting of 88.9%. Significant differences were found in the morphometric indicators of the root system: in the number of roots – 4.00 ± 0.41 pcs., compared to the control 2.52 ± 0.35 pcs.; the total root length – 6.24 ± 0.83 cm, compared to the control – 2.71 ± 0.40 cm. The maximum total shoot growth was obtained in a substrate with acidic peat using the mycorrhiza-forming preparation ‘Mycofriend’ and amounted 6.78 ± 0.88 cm, compared to the control 3.97 ± 0.25 cm. Conclusion. The information is useful in the scientific understanding of the rooting ability of ever- green plants ex vitro , using the black crowberry cultivar 'Irland' as an example. It could also help us to obtain high-quality planting material for large-scale commercial production.